Reference

MG: On Wednesday, I don't think anybody in the control room believed that that
could even happen. I mean they'd been taught in all of their training that
this was something that just -- the plant would not allow this to happen to
itself. And I don't think anybody in the control room believed that the core
was uncovered. We now know that at, I believe, eight-thirty in the morning
Wednesday, March the 29th, they were 30 minutes away from the "China Syndrome."
Had the decision not been made to close the blocked valve and re-start
emergency core cooling at that crucial instant, and had it been allowed to go
for another 30 minutes, they would have had a core melt-down that would have
made Chernobyl look like a picnic. If that had gone through the base of the
plant, we would now no longer be able to drive through the City of Harrisburg.
The Pennsylvania Turnpike would have to go north through Scranton. And you
have to remember that within a hundred-mile radius of this plant you have
Philadelphia, Baltimore, Washington, D.C. So this would not have been a
pleasant experience for anyone concerned. And they discovered -- of course, it
was years before they were able to actually open the lid on that thing and take
a look, but when they did take a look, hah-hah, they were horrified because
they could see that the entire core had slumped into the bottom of this vessel.
It was just a jumble of loose material, some of which had already turned to
liquid. So they were that close to a disaster of almost unimaginable
proportions.